Bypassing a kinase activity with an ATP-competitive drug
Bypassing a kinase activity with an ATP-competitive drug
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DOI：
10.1126/science.1090031
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发表时间：
2003-11-28
期刊：
影响因子：
56.9
通讯作者：
Walter, P
中科院分区：
文献类型：
--
作者：
Papa, FR;Zhang, C;Walter, P
内质网中未折叠的蛋白质引起双功能跨膜激酶IRE1的反式磷酸化，从而诱导其内核酸酶活性。内核核酸酶启动HAC1信使RNA的非惯性剪接，以触发展开的蛋白质反应（UPR）。我们通过通过位置定向的诱变对ATP竞争激素抑制剂1NM-PP1敏感，探索了IRE1激酶结构域的作用。矛盾的是，药物敏化的IRE1突变体不受1NM-PP1的抑制，需要1NM-PP1作为激活的辅助因子。在存在1NM-PP1的情况下，药物敏化的IRE1绕过突变，使其激酶活性失活并诱导完整的UPR。因此，而不是通过磷酸化本身，而是通过使用配体占用位点占用的激酶结构域的构象变化会导致所有已知的下游功能的激活。
Unfolded proteins in the endoplasmic reticulum cause trans-autophosphorylation of the bifunctional transmembrane kinase Ire1, which induces its endoribonuclease activity. The endoribonuclease initiates nonconventional splicing of HAC1 messenger RNA to trigger the unfolded-protein response (UPR). We explored the role of Ire1's kinase domain by sensitizing it through site-directed mutagenesis to the ATP-competitive inhibitor 1NM-PP1. Paradoxically, rather than being inhibited by 1NM-PP1, drug-sensitized Ire1 mutants required 1NM-PP1 as a cofactor for activation. In the presence of 1NM-PP1, drug-sensitized Ire1 bypassed mutations that inactivate its kinase activity and induced a full UPR. Thus, rather than through phosphorylation per se, a conformational change in the kinase domain triggered by occupancy of the active site with a ligand leads to activation of all known downstream functions.